This K23 award will provide Aaron Milstone, MD with the necessary resources and protected time to become an independent investigator performing patient-oriented research. In addition to the research studies, this proposal outlines a comprehensive career development program, including advanced coursework in epidemiology, biostatistics, and clinical trial methods and mentorship from a national leader in healthcare epidemiology in combination with a faculty advisory committee. The research component of this award will focus on methicillin-resistant Staphylococcus aureus (MRSA) in children with an emphasis on community-associated MRSA (CA-MRSA) strains. As CA-MRSA strains fuel an MRSA epidemic, the impact and control of MRSA requires further study. CA-MRSA strains are entering the hospital, being spread to children, and causing hospital-acquired infections and hospital outbreaks. The clinical spectrum of MRSA infection in children is well described. However, the epidemiology and impact of MRSA colonization and transmission in children is not well characterized. In addition, the virulence and transmissibility of CA-MRSA strains remains unclear. The pediatric intensive care unit (PICU) provides an environment amendable to studying the epidemiology, pathogenesis and prevention of MRSA. The proposed studies will 1) measure the prevalence of MRSA colonization and the incidence of MRSA transmission in a pediatric population and determine the distribution of various MRSA strains;2) determine the risk of MRSA infection in children colonized with different MRSA strains;and 3) assess the efficacy of bathing patients daily with chlorhexidine as a feasible strategy to reduce MRSA transmission. These studies will utilize the resources of The Johns Hopkins Hospital Department of Hospital Epidemiology and the Clinical Microbiology Laboratory. We anticipate that these studies will serve as a model for assessing the impact of multidrug-resistant bacteria in a pediatric population, and help guide the allocation of resources towards infection prevention strategies in hospitalized children. Future studies will use the archive of bacterial isolates and their associated clinical data to further characterize the pathogenicity of various MRSA strains. RELEVANCE: MRSA is a significant cause of disease and death in the United States and around the world. Because studies in adults show increased financial costs and mortality associated with MRSA, the epidemiology and impact of MRSA in children requires further study. Sound epidemiologic investigation and innovative and feasible interventions are needed to control MRSA transmission and prevent MRSA disease.